DE2215450A1 - Free jet servo valve - Google Patents

Description

Free jet servo valve

The invention relates to servovalves, in particular on very quickly responding hydraulic servo valves.

Such servo valves are used, for example, in aviation technology for controlling devices for preventing aircraft wheels from locking or for the Operation of aircraft control surfaces used. In this case, the servo valves are used to generate an electrical Signal into a pressure or a fluid throughput with the shortest possible response time and the highest possible accuracy to convert.

Servo valves with pistons are already known; With these valves, the fluid is distributed with the aid of a Establishment of changeable passage cross section between

efon 0821/330433 Telegr.-Adr .: ElPATENT

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ORfQlNAL INSfEGTEO

two chambers that are under different pressures.

The change in cross-section is based on the relative displacement between two components, between which more mechanical Contact exists, servo valves of this type are available as rotary slide valves or as piston slide valves with linear Piston displacement can be carried out.

Such servo valves are used less and less today because the machining of the parts is done with great accuracy and the clearance between the piston and the valve housing must be as low as possible.

Because of the little play and the sharp edges that the These valves are used to limit the passage cross-sections for the fluid very sensitive to contamination of the fluid, when the edges of the piston wear, leakage losses occur and play too.

Finally, it is also because of the relatively high frictional forces the hysteresis of these valves is considerable.

There are also known servo valves in which a servo motor drives a slide in a predetermined direction, which slide moved between two nozzles that are fed with high pressure fluid through a calibrated constriction in the cylindrical Part of each nozzle is provided.

The interior of each nozzle is connected to the working lines of the Fluids connected.

In servovalves of this type, the distance separating the end of each nozzle from the spool is small in relation to the Diameter of the nozzle opening,

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If it is required that the throughput of the nozzles themselves remains low at high pressure, you have to use throttles with a very small diameter and consequently a very Maintain a small amount of play (Q, 02 to 0.03 now).

So that the larger particles contained in the fluid can happen between the nozzle and the slide, if their play is very small, the fluid must be carefully filtered will, /

In addition, such particles destroy if they are large Speed are thrown against the slide, its surface and change the operation of the servo valve.

Valves with an orientable jet are also known in which the armature of a servomotor sets a nozzle that can be moved back and forth in rotation; through this nozzle the Fluid at high speed in the form of a jet that is distributed over two receiving openings.

If a torque is supplied to the armature of the servomotor, it is shifted the jet and the receiving openings consequently receive unequal amounts of fluid.

This valve can be used with all types of (also contaminated) Fluids are used, and the relatively large game allows fairly large tolerances in production.

However, this valve suffers from two major disadvantages:

- On the one hand, a flexible pipe is used between the back and forth uses moveable nozzle and servomotor · This tube is expensive and difficult to manufacture;

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- On the other hand, a flexible connection must be established between the high pressure supply line and the adjustable nozzle will. If the supply pressure is increased, this is A flexible connection can only be realized with difficulty, because it must have a rigidity corresponding to the calculated value own.

In addition, the inertia of the parts is relatively great is, you have to work with relatively powerful servomotors.

From French patent specification 1 5 97 27 6 valves are known in which one with the movable armature of the servomotor connected deflector has a flattened end which is provided with a vertical slot. Of the The slot is delimited on its vertical sides by a deflecting element forming flat surfaces which are mutually opposite incline in the direction of the flow of the fluid jet.

If the slot shifts across in front of a jet nozzle, the fluid jet is deflected and a different amount of fluid is obtained in the collecting channels.

In such valves, the fluid jet has an effect on the servomotor mainly when the angle of the deflector is quite large.

On the other hand, because of the opening of this angle, the contaminating particles contained in the oil, the tendency to have an erosive effect on the deflecting element and the element must be made of a very hard and abrasion-resistant material.

The object of the invention is a valve with a directable jet j in this valve

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- are subject to the movable. Parts rotating only;

- The rotational inertia of the moving parts is very low;

- the friction between the different parts is negligible; ·: '

- The fluid jet has practically no effect on the servomotor. "■■■ / ';■' ■ -: - \ - '- ."

Because of these four properties, a servomotor with a very low drive torque can be used. This servomotor therefore has a small footprint, which results in a very short response time of the motor for a given power *. ^:

Subject ^{7 of} the invention is also a valve without a flexible connection between the pressure source and the jet nozzle that discharges the fluid,

The invention is also intended to specify a valve of economical design and high operational reliability. .

The servo valve according to the invention is essentially provided with a drilled out valve housing and an alignable one Jet nozzle, a device for rotating the jet nozzle, a device that enables the rotation of the jet nozzle counteracts a collecting nozzle, the opening of which is the opening facing the jet nozzle, the fluid throughput in the collecting nozzle depends on the angular position of the jet nozzle. ' This servo valve is characterized in that the jet nozzle is rigidly connected to a cylindrical drum which is rotatable in a bore made in the valve housing is designed that a known hydrostatic Storage as a guide, the mechanical contact between the drum and that formed in the valve housing

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Prevents bore, and that a machined into the valve housing and opening into said bore feed opening for the jet nozzle is arranged so that the feed opening establishes a connection for pressure fluid with the jet nozzle for each usable angular position of the drum.

In one embodiment, the drum carrying the jet nozzle receives its position compensation by means of two pairs of hydrostatic ones Bearings which are provided at each one of the ends of the drum and are formed in the drum by surfaces which are hollow opposite the outside of the drum. Each hydrostatic bearing is controlled by an independent throttle line which represents the pressure drop for the supply line for each hydrostatic bearing.

The invention also relates to a preferred embodiment for the pressure drop when feeding the hydrostatic bearings of the drum carrying the jet nozzle and for centering the jet nozzle.

Another subject of the invention is an axial adjustment for the drum carrying the jet nozzle.

The subject of the invention is also preferably the angle adjustment the device serving the drum carrying the jet nozzle

An embodiment of a device that the drum in the absence of a control current for the control valve in returns to the neutral position also forms an object the invention.

Further features and advantages of the invention emerge from the following description of embodiments of the servo valve and with reference to the drawings that show:

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Fig. Γ a section through the servo valve;

Fig. 2 is a section through the holder for the jet nozzle * along the line II-II in FIG. 1 on a larger scale;

Figure 3 is a partial view of the end of the servo valve in Figure 3 ^; Direction of arrow, f in Fig. 1;

Fig. 4 shows a partial section through the servo valve along the line IV-IV in Fig. 1; -.- ■ - '' ■ - ' - ,.'.

5 shows a partial section through the servo valve;

6 shows a section through the holder for the jet nozzle along the line VI-VI in FIG. 5 on a larger scale. Scale;

7 shows a section through the holder for the jet nozzle along the line VII-VII in FIG. 5 on a larger scale ; - ■. ■■ ^; - -, -. · ■ -.- ". · ■: - ■ ..-".

Fig. 8 is a partial view of the end of the servo valve in the direction of of the arrow. F in Fig. 5;

Fig. 9 is a partial section through the servo valve along the Line IX-IX in Fig. 8 .;

Fig. 10 is a partial view of the end of the servo valve accordingly 8, but with the valve cap fitted;

11 is a plan view of the servo valve in the direction of the Arrow F 'in Fig. 10, partially cut along the Line XI-XI in Fig. 10; .

Fig.12 is a section through the support members of the nozzles of the Servovalve cut along the line XII-XII in

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Fig. 8 and on a larger scale:

13 shows a section through another embodiment of the servo valve.

In the following description are to be considered as parts of the invention only: the fluid jet generator, a Drive and guide device for this jet generator and the control means that respond to the input signal, especially if these means are designed as a servomotor.

The servo valve shown in FIG. 1 has a valve housing 101 with a bore 102. There is a drum in the hole 103 rotatably recorded. The jet nozzle 104, which is therefore located in the bore 102, passes diametrically through the drum 103 can rotate, but the nozzle can also be attached to the drum as a special component and located outside the drum are located. The diameter of the outlet opening 106 of the jet nozzle is adapted to the required beam diameter (depending on the area of application 0.2 mm to a few millimeters). In order to a non-widening, as cylindrical as possible jet is produced, only has the outlet opening 106 of the jet nozzle a relatively short length and is connected to the inlet opening of the jet nozzle in such a way that the velocity gradient is practically constant along the nozzle.

The jet nozzle 10H faces a feed line opening 108, which penetrates the valve housing 101. The opening 108 is supplied from the high pressure source of the servo valve.

If one wanted to try to rotate the drum 103 as long as the opening 108 is connected to high pressure, one would result

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significant frictional torque between the drum and the Bore, because the fluid pressure seeks the drum against the To press bore wall.

In order to remedy this evil, the opening is made 108 escaping pressure oil passed through a groove 109, which is milled in the longitudinal direction over the drum and in Druokab- ' case inducing chokes that run at each end of the Valve drum 103 are provided. As such throttles, for example, two grooves 110, 111 (one on each Drum end), which are generated by allowing the drum to rotate around an axis of rotation R that is parallel to their actual central axis 0 runs (see. Fig. 2). Each groove 110, 111 extends through a passage 112 and 113 with two pairs of surfaces of revolution 114 and 115 in connection, which are formed at each end of the drum and hydrostatic bearings offset at an angle with respect to the bearing of the same, attached to the same end of the drum 10 3 pair.

In this way, if the grooves 110, 111 are correctly calculated, the drum 103 in the vase known per se in hydrostatic bearings is in equilibrium between the effect caused by the force fl of the feed pressure and the two forces f2 and f3 at each end of the drum. There is therefore no mechanical contact between the drum 103 and the bore surface 102. ■ _: _

According to FIGS. 1 and 3, the movable armature 116 of the servomotor is rigidly connected to the drum 103. The servomotor 117 can be constructed in a manner known per se. A servomotor type "E 1" of the two windings B is shown having wound on each arm of the fixed part is. A permanent magnet N-S creates a polarized magnetic field, the lines of force of which correspond to the arrows D

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and E are closed »

When current flows through the windings B, they generate a Magnetic field, the lines of force of which are shown by the arrows G. According to known rules, the movable armature 116 of the servomotor is subjected to a moment that is proportional to the current flowing in the windings B. is. This moment is of course transferred to the drum 103. The fixed part of the servomotor is on attached to the valve housing 101 of the servo valve using a non-magnetic holder T »

The whole arrangement is exposed to the outside by a cap 118 completed, which is sealing against the block C, on which das.Ventilgehäuse 101 is attached. The one drawn The servo motor is located in the oil and is sealed off from the actual hydraulic fluid of the servo valve by flexible walls. In this way there is good cooling of the windings of the servomotor, and it is avoided that of Magnetic particles entrained in the hydraulic fluid can interfere with the operation of the servomotor. It is one of the characteristics the device that the resilient walls are stressed on torsion and that they form sleeves that through a first connection to the valve housing 101 and a second connection to the drum 103, wherein the latter connection is located between the movable armature 116 and the valve housing 101.

If the servomotor 117 is not fed, it is moved into a certain angular position by an elastic member 120 returned. As the elastic organ 120, a flexible Steel rod, which is fastened with its ends to the drum 103 or the valve housing 101, are used. In this way the orientation of the jet nozzle 104 can be varied by changing the abutment of the rod 120 on the housing 101

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ieren. If there is no current flowing through the servomotor, the jet emerging from the nozzle 10M- can be regulated so that it is evenly directed onto two collecting nozzles 121a and 121b, which can be seen in Fig. M-. These two Collecting nozzles are worked into a circular disk 122, the. between a cover 12 3 and a main part 124 · attached is, in which an axial oil discharge passage 125 and a corresponding radial passage 126 are cut, which with lines 127 and 12 8 of the housing 101 in connection and are to be connected to consumers who are located on surface 129 of block C. The gap between the jet nozzle 10M and the collecting nozzles 121a and 121b is through a line 130 with the schematic connected to the reservoir denoted by V. The various fluid connections are only indicated schematically because their design is known per se, and all hydraulic connections are routed to surface 129 of block C, as drawn in FIG.

If the servomotor is excited, the jet nozzle rotates 104 containing drum 103 and the jet spreads out unevenly on the collecting nozzles 321a and 121b. At the maximum torque of the motor 117, only one of the collecting nozzles receives it 121a, 121b the fluid ejector. In the other nozzle there is accordingly the pressure of the storage container with which it is over line 130 is connected. The thickness of the circular disk 122 must be very close to the beam diameter. Around to achieve this, the nozzles 104, 121a, 121b are assisted of adjustable axial stops 131a and 131b of the drum 103 are aligned with one another, as can be seen in FIG. 1 is. ·

The collecting nozzles 121a, 121b, the implementation of which is not the subject of the invention, could just as well by drilling Holes are made in a part, which is subsequently

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hardened and made wear-resistant by a suitable treatment.

The above description shows that in this way A jet generator of small dimensions that can be steered in different directions (the drum can be in a first Servo valve stage 5 mm in diameter and approximately 15 mm in length) and low inertia, the works smoothly. It also shows that the fluid jet has practically no effect on the servomotor · The servomotor can thus be made very small and simple be constructed.

The inventive device can, however, within the framework of Invention with any servomotor and any elastic restoring device for the beam generator be equipped.

Furthermore, the person skilled in the art can use the device according to the invention with an encapsulated servomotor or with one in fluid connection with the input pressure of the servo valve equip stationary servomotor,

There is also an embodiment for hydrostatic bearings (in the present case four independent bearings) with the required supply lines have been shown. The person skilled in the art can easily imagine that in the context of Invention other embodiments for the throttle lines and the hydrostatic bearings are possible.

In the embodiment according to FIGS. 5 to 12 arise the pressure drops in the supply of the hydrostatic bearings 114 and 115, the reference numerals of which are the letters D and G, respectively is attached, depending on whether the bearings are on the right or left side of the axis of the collecting nozzle (according to Fig. 5)

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located in the following way;

The drum 103a equipped with these bearings is mounted in a sleeve 203, whose from the high pressure source The supplied opening 108 is located opposite the jet nozzle 104 and the pressure fluid in a milled longitudinal groove 109 leads. The groove 109 supplies two bores 201, 202 cut radially into the sleeve 203. The sleeve 203 is inserted with a press fit or with very little play in the two housing parts 101a, 101b of the valve.

The drill holes 201 and 202 open "in a first sentence Annular grooves 204 and 205, which are in the "outer surface of the sleeve 203 are cut .. The groove 109 is so wide that the Bores 201 and 202 at any time during the usable rotation the drum 103a are supplied with high pressure fluid.

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Furthermore, the ring * grooves 206, 207 urid '^ 08; 209 of a second set of grooves cut and, as shown in FIG. 5, these grooves are located on one side of the J-grooves 204 and 205.

The groove 20.6 is via a radial bore 210 in the sleeve 203 with the cavity 115, G of the. Located at the left end of the drum hydrostatic bearing in connection. The groove 207 is through a radial bore 211 with 'the cavity

114G of the one located at the left end of the drum 103a hydrostatic bearing in connection, which is angularly offset from the hydrostatic bearing 115 G.

Bores 212 and 213 connect in a corresponding manner the grooves 208 and 209 with the cavities 114D and 115 "D of the hydrostatic bearings, - which are located at the right end of the drum 10" 3a · : ■ - ″ ■,. . ■ 'χ' - \ '

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Finally, the groove 20t of the first groove set is included the grooves 206 and 207 of the second set of grooves by a External thread 2m on the outer surface of the sleeve 203 connected, in the same way the groove 205 of the first groove set with the grooves 208 and 209 of the second set by an external thread 215 on the outer surface of the sleeve 203.

Each of these external threads 2m or 215 is divided by the grooves 20 ¹ I or 205 into two thread parts of the same length. Each of these threaded members provides an independent pressure drop for each of the _{bearings defined by their cavities 114G, 115G, 9} 114D, 115D.

The main advantage is that the pressure drop paths implemented in this way are relatively long and that therefore the cross-sections can be selected to be relatively large, so that there is no risk that they of Impurities that are entrained in the pressure fluid, can be added.

According to FIG. 8, the armature 116 of the servomotor is rigidly connected to a leaf spring. This numbered a total of 220 The spring has two wings 221 and 222 which are connected by a center piece 223 which is attached to the armature 116 of the servomotor is attached.

The middle piece 223 of the spring 220 forms a cover, the arms 22 3a and 223b of which lie on either side of the armature 116. The arms 223a, 223b and the movable armature 116 are non-rotatably connected and indeed with an extension of the Drum 103a, The rotation of parts 116, 22 3 relative to the Drum 103a can be tied off in any way, for example by riveting or gluing. The spring 220 is preferred made of a non-magical elastic material, made of bronze or beryllium, for example.

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It will be shown that this spring 220 is the nozzle bearing drum can adjust both angularly and axially. -;

The end of the wing 221 of the spring 220 rests against a cylindrical adjustment part 22H, the axis of which is parallel to the axis of the drum 103a. One end of the part 224 has an external thread 225 which is screwed into a threaded bore 226 which is located in the housing 101 of the valve. The second end of the part 224 has a cylindrical section 227 which is guided through the cap 118 of the valve in a sealed manner with a seal 228. The cylindrical section 227 is designed so that it can be rotated with the aid of a suitable tool, such as a screwdriver Width is equal to the width of the wing 221 of the spring 220. By rotating the part 224, this is displaced in the axial direction thanks to the thread 225 and as a result the spring 220 displaces and the drum 103a experiences a displacement in the axial direction.

This gives you an adjustment device for the axial position the drum 103a carrying the jet nozzle; -

Since the recess part 224 with the valve housing 101b is rigid connected, you can adjust the bare valve without its cap beforehand. But you can also have a final setting after the cap has been placed on the valve. . -. .

The end of the second wing 222 of the spring 220 leans' against an adjustable stop 229 (Fig. 10). The attack 2 29 consists of a threaded section 2 30 with

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rounded end 2 31; the thread is in the cap 118 of the Servovalve screwed. The stop 229 also has a screw head whose diameter is larger than that of the threaded section and which is provided with a seal 233, which seals the passage through the cap 118. Of the Stop 229 is therefore accessible from the outside when the servo valve is covered with the cap.

If the stop 229 is rotated, the rotational position of the drum 10 3a and thus the angular position of the jet nozzle and This ultimately also changes the distribution of the jet between the two collecting nozzles.

This adjustment of the drum is possible because the wing of the spring is non-rotatable with respect to the axis of the drum 103a is arranged.

So that the displacements between each spring wing and its stop when rotating the drum can be neglected, must be the line that marks the point of contact between the wing 221 of the spring 220 and the stop 224 with the point of contact from the rounded end 2 31 of the stop 22 9 and the wing 222 of the spring connects, precisely through the drum axis get lost.

The prestress exerted on the spring 220 by the stops 224 and 229 should be selected so that the contact force between the spring 220 and its stops for all usable angles of the position of the armature 116 of the servomotor in none Trap becomes zero. This can be achieved in practice by using the spring 220 from the form shown in FIG With the help of their stops, they are converted into the form shown in FIG.

The above description shows that the return spring 220 for the armature 116 of the servomotor is the axial

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and the wink! massive adjustment of the jet nozzle enables

The sleeve 203 is pressed into a portion 101a of the valve housing, for example, which has a certain thickness in the axial direction of the drum 103a so that the Jet nozzle 10t screwed out of the sleeve 203 and removed can be without this housing part 101a needing to be touched. .

The surface 234- of the housing part 101a is flat.

A ground plate 235 with flat side surfaces is placed with one side on the surface 2 34 ·. The second Surface of the plate 235 receives a thin disc 122a, the strength of which is practically equal to the diameter of the jet emanating from the nozzle 104.

The disc 122a is designed to accommodate the collection nozzles 121a and 121b for the beam (see Fig. 12). Finally, the second part of the valve housing is placed against the disc 122a and all of these parts 101b, 122a, 235 and 101a are screwed together with screws 237.

The sleeve 203 becomes perpendicular with very little or no Play in the plate 235 and in the thin disk 122a, so that leakage losses between the entry chamber for pressure fluid and the never of the pressure chamber 242 remain low. The collection nozzles 121a and 121b are in the disc 122a cut and stand with the two useful openings 240 and 241 through recesses in the parts lOlä, 101b in Compound, The disc 122a can be chemically removed getting produced. The collecting nozzles 121a, 121b are separated from each other by a wedge-shaped disk part separated j the acute wedge angle is against the jet nozzle

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directed

In another embodiment, that shown in FIG Valve housing consist of one piece 301 and the sleeve can be pressed in or with very little play be let in. In this case, a threaded plug 302 holds the sleeve in place and supplies it at the same time the jet nozzle with high pressure fluid supplied at HP.

A blind hole 30 3 is machined into the housing 301, the entrance of which is threaded. In the blind hole is low Game part 305 with seals 306 and 307 used, the chambers 308, 309 delimit the hydraulically against each other are isolated and each connected to one of the collecting nozzles and to a working opening.

A thin disk 310, in which the collecting nozzles in a known manner cut is placed against the part 305, and the disc is sealing against the part 305 by means of placed a pressure plate 311, which in turn is under the pressure of a threaded plug 312, which the hole 303 concludes.

The nozzle carrying drum 313 is adjustably mounted as previously described in connection with the drum 103a.

The servo valve according to the invention can be used as a control element can be used for a multi-stage servo valve. A servomotor has been described as an input element. Naturally Any other input element of mechanical or pneumatic type can also be used within the scope of the invention be used.

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The servo valve according to the invention finds the same commercial one Usage like the well-known Servoveritile,

These servo valves are suitable as hydraulic controls, especially for the operation of machine tools, Brakes and aircraft control surfaces. Because of its low manufacturing cost, the servovalve can be used in the automotive industry in devices for preventing the locking of brakes or for modulating the control pressure of the Couplings are used in automatic transmissions *

Patent claims;

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Claims (1)

Claims; 1. Free jet servo valve, with a drilled out housing, an adjustable jet nozzle, a device for rotating the jet nozzle, an elastic device, which counteracts the rotation of the jet nozzle, at least one collecting nozzle, the opening of which is the opening of the jet nozzle opposite, wherein the fluid throughput in the collecting nozzle depends on the angular position of the jet nozzle , characterized in that the jet nozzle (104) is rigidly connected to a cylindrical drum (103) which is rotatable in a bore (102) which is formed in the valve housing, that a known hydrostatic Storage as a guide to any mechanical contact between the drum and that formed in the valve housing Prevents bore, and that a machined in the valve housing and opens into said bore Feed opening (108) for the jet nozzle (104) is arranged so that the feed opening for each usable angular position of the drum establishes a connection for pressure fluid with the jet nozzle. Servo valve according to Claim 1, characterized in that the drum receiving the jet nozzle is connected to the movable drum Armature (116) of a servomotor is rigidly connected. 3p servo valve according to claim 3, characterized in that the servomotor is embedded in a fluid that is of the 209842/0838 221545 Q Fluid to the servo valve through a compliant wall (119) is separated in a manner known per se by a first connection on the valve housing and through a second connection on the drum itself is attached, and that the second connection is between the movable armature of the servomotor and the Valve housing is located. M. servo valve according to claim 1, characterized in that that the axis of the feed opening (108) for the Jet nozzle of the servo valve practically perpendicular to the axis of the hole for the drum in the middle part the axis of the bore and that the drum is relieved by two pairs of hydrostatic bearings ClIMi, 115) ,. which are located at one end of the drum ·, with each bearing offset by an angle from the Bearings of the same pair are through and in the drum Areas is formed that are hollow compared to the outer surface the drum lie and that each bearing through independent throttle lines (110, 111) is supplied. ■ 5. Servo valve according to claim M ,, characterized,, that the drum (103a) in one in the valve housing attached cylindrical sleeve (203Σ that the throttle lines for, the supply of the hydrostatic bearings for the relief of the drum in itself is formed in a known manner by external threads (214, 215) which are located on the outside of the sleeve and on both sides of a first set of grooves C20M-, 205), into which the threads open so that the grooves (2QM-, 205) 98 42/0 are machined into the outer surface of the sleeve (203) ^; and are connected to the feed opening (108) so that each thread also opens into a second set of grooves (206, 207, 208, 209) which are machined into the outer surface of the sleeve (203) so that the two grooves (206, 207 or 208, 209), which are assigned to the two hydrostatic bearings of one and the same pair, are arranged symmetrically to the groove of the first set of grooves, and that the grooves of the second set through a radial bore (210, 211) of the sleeve (203) respectively are assigned to one of the hydrostatic bearings. 6. Servo valve according to claim 1, characterized in that the elastic device, the rotation of the Opposite jet nozzle, has a leaf spring (220) which runs exactly perpendicular to the drum axis and is rigidly connected with its central part to the movable armature (116) of a servomotor that the two Ends (221, 222) of the spring extend on a first resp. second stop (22M-, 229), of which the second is changeable in its position in such a way that a change in its position changes the angular position of the brings about movable armature and that the spring is also biased by these stops such that the spring exerts a reaction force on the two stops at each moment exerted by the servomotor. 7. Servo valve according to claim 6, characterized in that that the first stop (224) of the spring (220) in a Direction parallel to the axis of the drum (103a) together 209842/0838 so displaceable with the end of the leaf spring (220) is that each position of the stop corresponds to an axial position of the drum carrying the jet nozzle Servo valve according to Claim 6, characterized in that the first and the second leaf spring stop represent two components with threaded sections that allow a position adjustment allow and that these sections lead sealingly through the housing of the servo valve and the actuating means protrude outwards. Servo valve according to Claim 5, characterized in that that the housing of the servo valve consists of at least two Sections (101a, 101b), which are screwed together on both sides of a thin disk (122a), whose Strength practically equal to the diameter of the jet emitted by the jet nozzle (104) is that the thin slice cut in a known manner is that two collecting nozzles (121a, 121b) are created which are separated from each other by a wedge-shaped piece acute angle is directed towards the jet nozzle that each collecting nozzle has a recess in one the valve housing parts (101a, 101b) are connected to the working openings (240, 241) of the servo valve, and that the thin disc is penetrated with very little play by the guide sleeve (203) of the drum (103a), whose axis is perpendicular to the disk surface in such a way that the jet emanating from the nozzle in the drum Aims exactly in the plane of the disc (122a) regardless of the angular position of the drum. 2 0 9 8 4 2/0838 .. 10. Servo valve according to claim 9, characterized in that between the thin disc (122a) and at least A disk (235) is provided in one of the housing parts (101a, 101b) forming the housing (101) of the valve in order to be able to dismantle the jet nozzle carried by the drum (10 3a) without the sleeve (203) must be taken out. 11. Servo valve according to claim 5, characterized in that the valve housing receiving the guide sleeve (203) (301) has a blind hole (303), the axis of which runs parallel to the drum axis, that a thin, disc (310) lying in the plane of the jet emanating from the jet nozzle carries jet collecting nozzles which are separated from each other by a wedge, of which. acute angle is directed against the beam that the thin disk (310) is clamped axially between two components (311 and 305) centered in the blind hole (303), and that one component (305) is arranged at the bottom of the blind hole (303) and is provided with seals in this way is that two chambers (308, 309) are formed with the bottom of the blind hole, which are hydraulically separated from each other and each with a hole on the one hand with a collecting nozzle and on the other hand with one in the Servo valve housing bored working port are connected. 209842 / OB 38 Read 11 e